1. Field of the Invention
This invention relates to communication methods, and in particular, it relates to a communication method that achieves pseudo-full duplex communication using a half duplex communication protocol.
2. Description of the Related Art
Conventional RS485 (also known as EIA-485) communication uses a master-slave arrangement, where the master initiates communication activities with a request and the slave answers. The system is a half-duplex system, as each device (master or slave) cannot transmit and receive at the same time. If the slave has data to be transferred to the master, the slave must wait until it receives the request from the master. If the time interval between the master's requests is relatively long, the data from the slave cannot be timely transferred to the master, causing delay in data transfer. Shortening the time interval between the master's requests, on the other hand, will increase the burden on the CPU of the master as well as the burden on the CPU of the slave.